Design Concepts: Random Thoughts...

[Bob Kolada]

It seems that most rotary tubas have the valves further on than most piston tubas which I believe accounts for much of the bore size difference. Compare a top valve 321 Bb (standard form for top valve tubas, shortest leadpipe), a front valve 2341 (standard form for most front piston vave tubas), and a 186 (standard form for most rotary tubas, longest leadpipe).

I had this typed out much more intelligently a few minutes ago, but the board seemed to freeze up and it didn't get saved. So whatever.....

[Rick Denney]

The bore is less relevant than the bell. Given that the bore at the valves is further long the bugle with a rotary tuba than with a piston tuba, one would expect the bore to be larger.

In my view, the bell down to and possibly including the bottom bow have the biggest effect on tone. The purpose of the bell is to act as an impedance matching device, to allow musically useful frequencies to make the jump from the tuba's resonant chamber to the outside world rather than getting damped and reflected back into the instrument. Thus, the bell has a huge impact on determining the harmonic makeup of the sound out front. So, a German tuba with an American bell will move in the direction of that blossomy American sound. The line between the two concepts is too fuzzy to allow a binary classification. My York Master has an American shape, but a German accent, despite the American plan, and largely I think because of the shape of the bell stack and bottom bow.

The taper design upstream from the bell affects which frequencies are amplified in the first place. I doubt that the bore has all that much effect on that in comparison. But I do think larger-bore tubas are more likely to be more broadbanded, in that the pitches can be bent without affecting tone to a greater extent. I can think of exceptions, however. And I suspect the taper design between the valves and the outer branches has the greatest effect on intonation tendencies.

Rick "suspecting that the way the package integrates can confuse the issue" Denney

[Ken Herrick]

In '67, while my King was being overhauled by Jerry, at Karnes, who had rebuilt Jakes York, I needed something to use and somehow got led to Fred Gottlieb who was selling his early Cerveny "Made in Bohemia" 4rv BBb. Fred told me that it was, in fact, the tuba H.N. White used as the "pattern" for designing the BBb monster rotary valve tubas.

It had a longer lead pipe than the King with a European receiver, which tapered down to the pipe which then had a length of small straight tube before expanding then about 4 inches of straight tube before it entered the valve body at .750in - same as the King. A difference was that the bore was progressive through all four valves and would have been about .820 at the 4th. It then had a straight section which continued through the main tuning slide. As I recall the bell was nearly the same diameter as the King but the general taper was more gradual than the King (I think it was about 19" vs 20").

This horn needed some work so I took it to Carl Geyer who refitted the valves, repaired the nearly flattened 4th valve tubing. and a few other things. He didn't have time to make a new lead pipe so removed some dents and did a couple patches. He said I should try a new lead pipe for it when we had the time available to work on it. I never got to have him do that job. I did some experimenting later and removed the mp receiver and flared the entry to the lead pipe so the mouthpiece went directly into it. I then cut out the 4 inches of straight pipe from the valve end of the lead pipe and ran it into the valve body. All up I would have shortened it by almost 6 inches which got it to where it was up to pitch which tended to be taken as A442 being pretty much the standard around Chicago at that time.

These changes made a very noticeable change in sound, respose, and tuning of partials., and made it play much more like the King which I and several others, including Jake, felt was the better instrument. Much of what was gained by the progressive bore through the valves had been negated by the straight lengths in the lead pipe and through the tuning slide. It was as if the rest of the horn had to catch up with the taper.

The King had virtually no straight tubing except through the valve body and about six inches on either side of the tuning slide which led Carl to tell Jake not to try cutting a King to CC as it would require cutting at the branch joins, resulting in distorting the taper. I believe Sam Gnagey has modified some of the Kings to CC with a shorter lead pipe to a piston valve block which would make up a lot of the amount to be cut. With that sort of alterations you would find a King monster BBb cut to CC would be very similar to the York. It would be VERY interesting to have Gene make a direct comparison between them and I would not be at all surprised if he secretly thought 'hmmm, now I could own one'.........

Some people did not like the string action valves. I found that by using braided fishing fly line and threading it so it locked the screw into the stop arm i did not have to worry about breakages, they were quiet and not subject to damage and locking up due to some minor bump and I could adjust the height of each key to suit me and with the short travel were very fast. When I taught others, including a lot of french horn players, how to thread their valves this way they too preffered them to the mechanical linkages which were available then. When I re-strung the 7V Alex F Jake said he wished he had known to do that when he was playing it.

Just a bit of extra trivia.............